independent

Tuesday 25 September 2018

Stunning marine life in canyon off coast of Ireland

A coral reef with a number of different marine species.
A coral reef with a number of different marine species.

Jim Hurley - Nature Trail

When you are informed that the image above is mainly of corals you may immediately conjure up an image in your mind of a coral reef bathed in warm, tropical or sub-tropical seas somewhere sunny, far away.

A nice thought but you would be wrong; the image is of cold water corals growing in the dark off the west coast of Ireland on the edge of the continental shelf.

The image was captured by a team of scientists from across the globe onboard the RV Celtic Explorer, led by a group of Irish scientists from University College Cork's School of Biological, Earth and Environmental Sciences. The scientists were involved in cutting-edge research in extreme marine environments.

Using state-of-the-art mapping technologies and the Marine Institute's Holland 1 Remotely Operated Vehicle, they mapped 1,800km2 of the seabed, an area twice the size of Malta, revealing stunning details of life in a submarine canyon on the edge of Ireland's continental shelf, 320km west of Dingle.

The major gash in the ocean floor is the Porcupine Bank Canyon, a landform with steep-cliffed edges and cold-water coral mounds. This vast submarine canyon system is bordered by near-vertical 700m cliffs that plunge to depths of 3,000m in places. Ten Eiffel towers could be stacked on top of each other to cover the vertical distance from canyon floor to canyon top.

The Porcupine Bank Canyon is the westernmost submarine canyon on the contiguous Irish margin and exits onto the abyssal plain at 4,000m water depth. The upper canyon is full of cold-water corals forming reefs and mounds which create a rim on the lip of the canyon 30m tall and 28km long.

The coral reefs on the rim of the canyon eventually break off and slide down the canyon walls where they form an accumulation of coral rubble deeper within the canyon.

The ocean absorbs carbon dioxide gas at its surface and the gas is extracted from the water by plankton. The corals get their carbon from dead plankton raining down from the ocean surface. The gas ends up stored on the ocean floor.

The Porcupine Bank Canyon can therefore be used to feel, as it were, the pulse of the changing Atlantic in an attempt to understand more about how submarine canyons help transport carbon from the atmosphere to the deep ocean and their role in combatting global warming and climate change.

In investigating these matters, Ireland is world-class, a small country punching above its weight.

Drogheda Independent

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